Baseband signal generator for digital modulator

摘要

A baseband signal generator according to the present invention performs differential encoding and mapping processings for a digital baseband signal and limits bandwidths of the obtained symbol mapping data of an I phase and a Q phase by digital filters. Each digital filter includes a circuit for accumulating symbol mapping data corresponding to a plurality of symbol sections, a plurality of ROMs provided corresponding to the plurality of symbol sections for storing symbol data corresponding to a predetermined filter waveform, and an adder for adding symbol data output from there ROMs. The adder outputs a digital baseband signal whose bandwidth is limited, which signal is converted into an analog baseband signal by a D/A converter and supplied to an analog modulation unit.